The use of social media does not cause division so much as amplify it.
The financial crisis of 2007-08 stoked popular anger at a wealthy elite that had left everyone else behind.
The culture wars have split voters by identity rather than class.
Nor are social media alone in their power to polarise—just look at cable TV and talk radio.
But, whereas Fox News is familiar, social media platforms are new and still poorly understood.
And, because of how they work, they wield extraordinary influence.
They make their money by putting photos, personal posts, news stories and ads in front of you.
Because they can measure how you react, they know just how to get under your skin.
They collect data about you in order to have algorithms to determine what will catch your eye, in an “attention economy” that keeps users scrolling, clicking and sharing again and again and again.
Anyone setting out to shape opinion can produce dozens of ads, analyse them and see which is hardest to resist.
The result is compelling: one study found that users in rich countries touch their phones 2,600 times a day.
It would be wonderful if such a system helped wisdom and truth rise to the surface.
But, whatever Keats said, truth is not beauty so much as it is hard work—especially when you disagree with it.
Everyone who has scrolled through Facebook knows how, instead of imparting wisdom, the system dishes out compulsive stuff that tends to reinforce people's biases.
This aggravates the politics of contempt that took hold, in the United States at least, in the 1990s.